Dean Mouhtaropoulos/Getty Image Boris Johnson, the former London mayor, led the campaign for Britain to leave the European Union and now, after a dramatic prime minister race, will be serving in one of the UK's top positions.

Originally hailed as David Cameron's likely replacement as prime minister, Johnson said he would not seek the position after his ally Michael Gove announced his own candidacy.

Johnson is a clownish character, but he has enviable popularity levels and is known by his first name across the UK. He is even affectionately referred to as "BoJo" over social media.

Here are some pictures of his life and rise to power.

This article was originally written by Mike Bird and updated by Caroline Simon.

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While at Oxford University, Boris was president of the Oxford Union, a position held by former Conservative leader William Hague and ex-Prime Minister Edward Heath.

REUTERS/Brian Smith PN

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Johnson went to Eton College and university with David Cameron, but Boris was much more obviously political at the time.

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Johnson was sacked after a brief career at the London-based newspaper The Times, and he then worked for The Daily Telegraph as the paper's Brussels correspondent, gaining a name for himself in the center-right press.

He also made a big deal of bringing back London's Routemaster buses, replacing the "bendy buses" that were used under Livingstone.

In 2012, as part of a promotional event for the Olympics, Boris was stuck on a zip wire.

In 2012, Boris won reelection as mayor in another contest against Ken Livingstone, winning by a smaller margin. London generally tends to vote more for the Labour Party.

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Boris has kept a constant media profile. With no major gaffes in quite some time, the idea of his leading the Tory Party has become increasingly realistic.

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But his critics called him an inactive mayor, using the position to boost his personal publicity. Here he is with BBC presenter Jeremy Paxman on a tandem bike.

BBC

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His popularity figures are perpetually high, regularly beating all other British politicians. A poll in June 2014 showed him 13 points clear of David Cameron.

Rob Stothard Getty Images

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Boris announced in August 2014 that he would run in the coming general election.

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In May 2015, Boris won the Parliament seat in Uxbridge, while the Conservative victory gave Cameron a second term as prime minister.

Rajanish Kakade / AP Images

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After rumors circulated in October 2015 that Cameron would step down early, Boris' name floated around as a possible replacement. Cameron had mentioned him as a possible successor when he said that he would serve only two terms.

REUTERS/Luke McGregor

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As debate over the Brexit heated up in early 2016, Boris said that his country had a "great, great future" outside the EU but that he'd rather see the UK remain in a reformed EU.

Oleg Popov / REUTERS

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On February 21, Boris Johnson officially came out in favor of Britain leaving the EU, giving the "Leave" campaign a significant boost.

Peter Nicholls/Reuters

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In March, Boris told a Treasury committee that there were "no good economic arguments" for Britain staying in the EU.